Improvement in materials for filling safes



HERMANN c. HAHN, or WYANDOTTE, AssreNon To HIMSELF, SIGMUND nornscnnin, AND ARNOLD KAIGHEN, or DETROIT, AND cHAnLns L. o trMA N, or EAST sAeiNAw, MICHIGAN.

IMPROVEMENT IN MATERlALS FOR FILLING SAFES, 85c.

Specification forming part of Letters Patent No. 126,049, dated April 23, 1872.

Specification of an Improved Fire- Proof Material or Composition for Safes and other structures, invented by HERMANN O. HAHN, of Wyandotte, in the county of Wayne, State of Michigan.

My invention relates to an improved fireproof or non-conducting material for filling safes, vaults, refrigerators, or the walls, doors, or shutters of buildings, or for covering boilers, furnaces, 850., to prevent the escape of heat, or the exposure thereto of surrounding objects.

I. My invention consists, in part, in the use of magnesia, carbonate of magnesia, borate of magnesia, phosphate of magnesia, chloride of magnesium, or any hydrate or anhydrite mineral which, after drying and roasting, will contain twenty-five per cent. or more of pure magnesia. As examples of the materials which may be used for this purpose, either alone or two or more of them compounded together, some of which contain magnesia, as aforesaid, I mention as the most important the following, designated, according to Danas nomenclature, magnesite, hydromagnesite, dolomite, hydrodolomite, brucite, ankerite, epsomite, talc, serpentine, pyroxene, amphibole, mendozite, chondrodite, phlogapite, biolite, boracite, carnalite, or the residuum of certain bitter water from the salt manufacture, containing, when dried and roasted, twenty-five per cent. or more of pure magnesia.

In applying this part of my inventionI take one or several of the above-named or any other equivalent material, but especially so magnesia or carbonate of magnesia, or burned magnesite, hydromagnesite, brucite, 850., and crush them to a very fine powder and mix them, if several combinations, together. I then make, with water, a thick paste, of about the consistence of brick-clay mass, and stamp it very tightly in the space between the walls of the safe, vault, refrigerator, or other structure which has to be filled; or I form blocks of said paste, of a convenient length and width, and of the full thickness of the space which is to be filled, and dry such blocks at a temperature not above 212 Fahrenheit; and, if they are made fiom magnesia, burned magnesitc, hydromagnesite, 860.,01' such substances which contain free magnesia, in an atmosphere of carbonic acid, which may be produced by an open fire burning in a closed room. In filling a safe, refrigerator, 850., with such blocks, a pulp of the same mass of which they are made is used as mortar to connect the blocks and fill all the open spaces, as broken corners, 8x0.

Magnesia, carbonate of magnesia, magne site, hydromagnesite, serpentine, and several the iron platesof the safe or other metals in their vicinity.

Instead of using one magnesia material it is better to mix several together, which increases the intended effect, and particularly I recommend magnesia or carbonate of magnesia, with silicate and sulphate of magnesia, and to mix the whole with ten to twenty parts of sulphate of iron, (0opperas,) or enough to color the dry mass yellow-red or red. For this latter purpose it is good to dissolve the sulphate of iron in the water which is used to make a paste from the dry materials.

The volume of the magnesia varies so very much, according to the way of fabrication, that I will give, beside the volume, the weight, but would recommend to make the mixture according to the given volumes. light magnesia usta.

A good mixture of this kind is 5 volumes: 29 pounds burned magnesia, burned magnesite, hydromagnesite, 810.

20 pounds sulphate of iron.

1 volume 1 volume 10 volumes 100 pounds.

II. I employ one or a mixture of several of I always used 35 pounds silicate of magnesite, talc,

the above-named or any other materials, but especially magnesia, carbonate of magnesia, and sulphate of magnesia, with anhydrite, lime, dolomite. ankerite, or any other substance containing lime in a large amount, raw or burned, for the purpose set forth herein.

Anhydrite, plaster-of P-aris, burned gypsum, or an y other substance containing anhydrated sulphate of lime in sufficient quantity,.gives, with water, a pulp which hardens in a short time to a hard mass, and is, therefore, well adapted to be cast in blocks or plates. Besides that, sulphate of lime is a very good non-conductor of the heat, and does not radiate the heat much.

instead of anhydrite, burned lime, ordolomite, or ankerite may be used in connection with sulphate of magnesia, which produces sulphate of lime and magnesia; or with sulphate of iron, which produces sulphate of lime and protoxide of iron. These latter mixtures, with lime or dolomite, harden slower than with anhydrite, and are, therefore, more convenient. If burned dolomite or a-nkerite is used instead of lime, their amount may, according their percentage of magnesia, be increased, and the amount of the magnesia de creased. Raw lime, dolomite, or ankerite cannot be used if a hard mass shall result, because they do not decompose sulphate of magnesia, but they decompose sulphate of iron, but very slowly. Mixtures of this kind are very good for covering boilers, furnaces, floors, doors, &c., to exclude fire.

Such mixtures are made with water to a pulp, and cast in the space between the walls of a safe, vault, &c., or put with a trowel upon the outside of a furnace, boiler, &c., but if the mass is intended for a safe, vault, 810., it is better to cast it in blocks or plates, which are dried in an atmosphere of carbonic acid, atnot above 212 Fahrenheit, and put between the walls of said safe, &c., using pulp of the same kind as mortar, and to fill all open spaces. Good mixtures of that kind are- 6 volumes 36 pounds magnesia, burned magn esite,

' hydromagnesite, Sac.

pounds silicate of magnesia.

pounds anhydrite, plastcr-of-Paris.

pounds sulphate of iron.

2 volumes 2 24 1 volume :20 1 volume :20

III. I also use mixtures of one, or some of the above named, or any other equivalent niaterial, with kaolin clay, sulphate of alumina,

or any other substance containing alumina in a large amount. Alumina is the best non-conductor of the heat next to magnesia. Substances which contain this earth are therefore very good as substitutes for magnesia to a certain degree.

Kaolin or clay gives, with water, a very plastie mass which is a good medium to form the magnesia in plates orto make a good paste out of it. Alum and sulphate of alumina have this same property, it they are mixed with a substance which separates the alumina from the sulphuric acid, which is in those salts contained. This effect is produced by lime, and moves slowly by magnesia. These mixtures particularly stand a very high heat without any change.

The fine-ground mixed materials are made with water, or a solution of sulphate of iron to a thick paste, and used as the mass under No. I. Good mixtures of such kind are- 5.5 volumes :7 27 pounds magnesia. 1.8 volumes 2 23 pounds sulphate of magnesia.

2 volumes 39 pounds fire clay. 0.7 volumes 2 11 pounds sulphate of iron.

I) volumes 100 pounds.

6 volumes 15 pounds magnesia. 2% volumes 12 pounds silicate of magnesia, and

63 pounds crystalized sulphate of alumina.

1%- volumes 10 pounds sulphate of iron.

10 Volumes 100 pounds.

In regard to materials to be used for filling fire-proof safes, vaults, 850., for covering boilers, furnaces, floors, &c., we have to look out for such substances, which, first, are not destroyed by fire nor so decomposed that the products are unfit for the intended purpose; second, do not melt or shrink considerably at a high temperature; third, are not converted into vapors by fire; fourth, reflect the heat of fire; fifth, have a high specific heat; sixth, do not conduct the heat; seventh, do not radiate the heat.

First, substances which cannot stand avery high temperature without such decomposition that the products are unfit for the intendedpurpose, are of course unfit for said purpose. To such material belong the most organic substances, particularly those which contain carbon; further, many nitrates (combinations of nitric acid with a base.) 1 will mention here some-which are patented for the purpose set forth herein. Paper, fibrous pulp, paper pulp, cotton, sawdust, starch, sulphate of iron, asbestus with glycerine, gelatine or mucilage, gutta-percha, caoutchouc. On the other side are the pure earths, and the most sulphates, silicates, borates, and phosphates of the earths, especially the bases, or salts non-combustible, non-decomposable, and non-fusible.

Second, substances which melt in a higher temperature (to) conduct the heat better than solid substances, not because all solid substances are better non-conductors of the heat than liquid substances; but the hotter (outer) parts of the melted mass is easier mixed with the colder (inner) part. (b) The melted mass is apt to leak out at adefective place of the safe, vault, 8m, and certainly if the outside plate or wall should be destroyed or burned through (0) even those substances which shrink very much are not good for our purpose, because a great shrinkage produces an open space, and if the outer wall should be destroyed, the fire would reach the inner wall directly at such points.

To this class of combinations belong sulphate of lime, sulphate of soda, carbonate of soda, biborate of sodaall, if notmixed with a sufiicient amount of other non-fusible substances. The most difficult salts to fuse'are those named under division I. Lime and ma gnesia are not fusible at a temperature where platina melts.

Third, substances which are converted by fire into vapors entirely, or so much that the substance left does not fill out the whole space taken before, are also unfit for said purpose. To this class belong water, all ammoniacal salts, crystallized sulphate of soda, crystallized carbonate of soda, all kinds of alums, crystallized sulphate of aluminathe latter salts, if not mixed with a large amount of other substances which do not contain water of crystallization. The reason why these substances are unfit for filling safes, vaults, &(3., is the same mentioned before. If the outer wall'is destroyed the fire will reach the inner wall directly. In spite of the fact the iron plates of safes become oxidized, and crumble to pieces under the influence of fire. There are many patents taken out based upon the good properties of water, or steam, or salts containing one-half of their weight water.

Fourth, materials which do not reflect the heat at all are likewise unfit, for example lampblack, bone-black, &c.

Fifth, substances which have a low specific heat cannot be used for the purpose set forth.

I will shortly explain the expression of specific heat and show the importance of a high specific heat. The relative amount of heat which raises the temperature of a given weight of distilled water one degree is called 1. To

raise the temperature of the same weight of iron one degree requires but 0.1138 of the amount of heat which was required to heat the water. 0.1138 is, therefore, called the specific heat of iron. The lower the specific heat of a substance is the more easily is it heated. When the outside wall of a safe in a burning building has a heat of 3,600 where cast-iron melts, a filling made from burned lime would, where it touches the iron, show only 2,000 and if the filling were made of burned magnesia the same side would be only 1,420 hot, because the specific heat of lime is 0.205 and that of magnesia 0.288.

All metals have a low specific heat, the earths have a higher one, magnesia being the highest. Garbonates and sulphates seem to have a nearly equal specific heat. That of the pure earths is lower. Then follow the silicates, phosphates, fluorides, and chlorides. Water, steam, and hydrogen have high specific heats; but if we compare equal volumes,which wehave to do in our case-that is, multiply the specific heat of a'substance with its specific gravity we find, if we use the specific gravity of the most compact magnesia, of the periclase, that magnesia has a higher specific heat than any other substance-at least, any whose specific heat is known.

Sixth, all the substances which have a low specific heat are generally conductors of heat,

but this property is not exactly corresponding with the specific heat, neither with the atomic weight, or the specific gravity. Therefore, all metals are good conductors of heat. Water, porcelain, glass, marble, &c., are not good conductors- According to the few experiments with so-called non-conductors it appears to me that the pure earths are the worst conductors of heat. Then follow the silicates, carbonates, and sulphates, also nearly according to their specific heat.

Seventh, the experiments with substances which radiate the heat-that is, let'a certain amount or rather certain rays of heat pass through-have not yet shown a distinct law; but it seems that their relative capacity to radiate heat is in the following, commencing with the worst: sulphates, silicates, carbonates, fluorides, chlorides, magnesia salts, alumina salts, calcia salts, potassa salts. We see instantly that these orders are exactly or nearly according to the specific heat of the salts. The kind of acid in a salt seems to be more important in regard to this property than the kind of base. Hence I found that silicates and sulphates are complementary for heatthat is, rays of heat which are not absorbed by a silicate will be absorbed by a sulphate. A good safe filling should therefore contain both kinds of salts. A thin plate of a salt absorbs a certain amount of certain kinds of heat which reach the plate; by increasing the thickness of the plate that amount is not increased proportionally, but to a very small degree. We do not need, therefore, to compose the whole filling of a safe, vault, &c., of silicates and sulphates, but make the larger portion of pure earths or carbonates. Another fact is that red or yellow-red bodies absorb more and pass less heat through than colorless or differently-colored bodies of the same composition. I add, therefore, an amount of sulphate of iron to my compositions for safe fillings, &c., which is enough to impart to said mass a distinct reddish hue. Sulphate of iron is decomposed by magnesia or lime and protoxide of iron precipitated, which by absorption of oxygen is converted into red peroxide of iron. Experiments with a small safe filled with a mixture of different salts combining the various useful properties named showed me generally the correctness of the above-explained laws.

My compositions contain generally, in ten volumes, five to seven volumes earths or carbonates, two to three volumes silicates, one to two volumes sulphates, with such an amount of water of crystallization that the mass will not dissolve in said water when it is liberated, and will not shrink when said water is evaporated. Further, I make the mass basic enough that it does not melt, even in averyhigh temperature.

Magnesia, magnesite, hydromagnesite, carbonate of magnesia, chloride of magnesium, heated to a sufficient high temperature, where it does not shrink any more, readily combines with water and carbonic acid to form hydrated carbonate of magnesia, which, as satefilling, envelops water and carbonic acid, both very poor conductors of heat, without changing its volume.

This invention, in addition to its use as a filling for the Walls of safes, vaults, &c., is also Valuable as a lining or filling for iron columns, and for compartment walls and fire-proof partitions in ships and buildings, and as a protection for receptacles for gunpowder and other inflammable matter.

Claims.

I claim as my invention- 1. Magnesia, carbonate of magnesia, sulphate of magnesia, silicate of magnesia, borate of magnesia, phosphate of magnesia, chloride of magnesium, or other salt or mixture, mineral or fabricate, which contains after burning (roasting) twenty-five or more per cent. of pure magnesia, but especially magnesia and carbonate of magnesia, to use one or several mixed as a non-combustible and non-conductive material for filling fire-proof safes, vaults, walls, refrigerators, floors, doors, or shutters for buildings, &c., to exclude the heat of the fire, to'reach the interior of said safe, vault, or building; also, to envelop fire by covering with said material boilers, furnaces, &c., to prevent the excess of the heat of the fire being communicated to surrounding objects, as on board of vessels, &c.

2.- A mixture of one or some of the abovenamed or other magnesia salt, and especially magnesia, carbonate of magnesia, and sulphate of magnesia, with lime, dolomite, ankerite, anhydrite, or with any other substance containing lime in a large amount, raw or burned, for the purpose above explained.

3. A mixture of one or some of the abovenamed or other magnesia salt, and especially magnesia and carbonate of magnesia, with kaolin, fire-clay, sulphate of alumina, or other substance containing alumina in a large amount, for the purpose above named.

HERMANN O. HAHN.

Witnesses:

ARNOLD KAIOHEN, SIGMUND Ro'rHscHILD. 

